The present invention relates to a magneto-optical recording/reproducing apparatus. In particular, it relates to a magneto-optical recording/reproducing apparatus which comprises an apparatus for applying a bias magnetic field to a recording medium during recording and erasing operations, and a mechanism for making the bias magnetic field applying apparatus close to and apart from the recording medium.
Recently, an optical disk apparatus which uses an optical disk as a recording medium is available for a recording/reproducing apparatus of large capacity. The apparatus is widely used for electronic storage or filing. However, in general, it is impossible to rewrite information written on the optical disk. In contrast, a magneto-optical recording/reproducing apparatus is an optical disk apparatus which can rewrite and erase the information. The magneto-optical recording/reproducing apparatus uses the magneto-optical effect.
As disclosed in various publications, information recording using the magneto-optical effect is conducted by the following procedures.
First, a recording medium is provided, which includes a substrate, and a perpendicularly magnetized magnetic film on the substrate. An optical beam, e.g. a laser beam, is focussed in to a 1.5 .mu.m diameter spot and irradiates that perpendicularly magnetized magnetic field film of the recording medium. Accordingly, the film temperature rises locally to a level in which the perpendicularly magnetized magnetic field film loses its ferromagnetic properties, i.e., to the Curie temperature. Simultaneously, a bias magnetic field is applied to a part of the perpendicular magnetic film, a temperature of which rises, to reverse the direction of magnetization thereof. The bias magnetic field applying apparatus may be a permanent magnet or an electromagnet. In order to carry out a stable recording, it is required to obtain a desired intensity of bias magnetic field by means of making the bias magnetic field applying apparatus as close to the recording medium as possible.
On the other hand, to protect the recording medium, e.g. the optical disk, and to facilitate handling thereof, the recording medium is usually enveloped by a specific casing or a cartridge.
Further, the recording/reproducing apparatus necessarily equipped with a cartridge carrying mechanism for mounting the cartridge, envelopping therein the recording medium, into the recording/reproducing apparatus and for moving the cartridge into a loading position in which the recording and reproducing operations can be carried out.
Therefore, the recording/reproducing apparatus necessitates a mechanism for making the bias magnetic field applying apparatus close to and apart from the recording medium. Namely, in case that the cartridge is to be inserted into the recording/reproducing apparatus and to be loaded into a predetermined loading position, the bias magnetic field applying apparatus is required to be apart from the recording medium so as to prevent the bias magnetic field applying apparatus from blocking off an insert passage of the cartridge. To the contrary, in case that the recording medium is loaded into the predetermined loading position, the bias magnetic field applying apparatus is required to be sufficiently close to the recording medium.
To this end, a recording/reproducing apparatus disclosed in JP-A-60-251541 is provided with a pivotable member, an end portion of which the bias magnetic field applying apparatus is attached, in addition to the cartridge carrying mechanism. The pivotable member is linked with a pivotable clamping member for clamping the recording medium onto a turn table so that it swings to make the bias magnetic field applying apparatus close to and apart from the recording medium.
In a recording/reproducing apparatus disclosed in JP-U-62-202601, upon an insertion of the cartridge, the bias magnetic field applying apparatus is abutted by the cartridge and is drawn back against a spring.
The recording/reproducing apparatus according to JP-A-60-251541 necessitates a separate pivotable member in addition to the cartridge carrying mechanism and places a pivot of the pivotable member away from the recording medium. Therefore, on the operation of the pivotable members, an arc stroke thereof is enlarged to make the recording/reproducing apparatus large.
In the recording/reproducing apparatus disclosed in JP-U-62-202601, since an edge of the cartridge necessarily abuts with the bias magnetic field applying apparatus every time the cartridge is inserted into the recording/reproducing apparatus, an impact load would be applied to the bias magnetic field applying apparatus. Accordingly the cartridge may be damaged seriously making it hard to obtain long term high reliability, and smooth insertion into the apparatus.